Peculiarities of postpyrogene development of algae in steppe biocenoses at Askania Nova Biospheric National Park

Features of groups of soil algae in steppe biocenoses with different durations of postpyrogene development after one or two fires within the natural core of the Askania Nova Biospheric National Park have been studied. It is found that the pyrogenic factor has a significant influence on the formation of steppe algal groups, showing their ability to quickly and fully use changes in environmental conditions. The number of species, ratio of major divisions, dominant complex, and range of life forms change in postpyrogene algal groups. There is an increase in the total number of species, especially heliophilous Cyanophyta, in steppe biocenoses exposed to the pyrogenic effect twice. Among dominants in studied biocenoses, species with different resistances to the pyrogenic factor have been noted. In all studied biocenoses, the richest algal groups in species composition form in summer and autumn. Cyanophyta, Chlorophyta, and Bacillariophyta are quite diverse in summer. The share of Cyanophyta increases in spring; Eustigmatophyta and Xanthophyta are more diverse in autumn. Most species of algae have been recorded in the upper 5 cm of soil. The number of species of Cyanophyta, unlike members of other divisions and, especially, Bacillariophyta, is sharply reduced with depth (up to 15 cm).